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Calculation of generalized spin stiffness constant of strongly correlated doped quantum antiferromagnet on two-dimensional lattice and it’s application to effective exchange constant for semi-itinerant systems

“…As stated earlier, the effective exchange constants of some itinerant magnets like Fe, Ni, Gd have been determined using the techniques based on 'inverse susceptibility'. Moreover, the exchange correlation in itinerant magnets can be expressed in terms of the elements of scattering path matrix in the framework of density functional approach [37,40,41]. Band structure calculation based on multiplescattering theory and spin-spiral techniques has also been done for estimating the exchange interaction in these itinerant magnets [41].…”

“…The effective exchange constant involving the nearest neighbour spins is related to the second order derivative of the magnetic energy with respect to the spin fields. Making use of this formalism the effective exchange constant turns out to be the inverse dynamic magnetic susceptibility (DMS), with some assumptions for the weakly interacting systems [40]. All these approaches described above, show that there has been ongoing theoretical research to determine the exchange constant and study the short range correlations even in weakly correlated itinerant magnetic systems, which is still a challenging problem in the field of condensed matter physics.…”

“…There were a few attempts to study the properties of conventional itinerant magnetic systems using coherent-potential, where local exchange-correlation approximation was used in the band calculations [39]. Later Antropov calculated the effective exchange coupling of the itinerant systems using a combination of 'inverse susceptibility' approach and multiple-scattering theory [40,41]. However, the above techniques and calculations were rather insufficient to determine the effective exchange coupling and magnetic interactions in the itinerant systems in the presence of strong Coulomb correlations.…”